What are the most common mistakes in choosing hydraulic components?

The rated working pressure of a hydraulic pump should generally be 25-60% higher than its maximum working pressure. The maximum pressure listed on the product sample refers to the pressure that is allowed for short-term impact. Therefore, it is crucial to avoid having impact pressures during each working cycle, as this can shorten the hydraulic pump's service life or even cause damage. The relief pressure should not be too high, as this can easily damage the oil pump.

The hydraulic cylinder is the actuator of the entire hydraulic system, so its selection is particularly important. Non-standard cylinders should not be used, and the safety factor of the hydraulic cylinder should not be too small. The cylinder barrel, ear rings, and pin shafts should not be neglected in terms of geometric tolerances. To reduce pneumatic pressure in the hydraulic cylinder and prevent the phenomenon of "stalling" during motion, sufficient attention should be given to the positional and dimensional tolerances of the hydraulic cylinder.

The hydraulic motor is also a key actuator in hydraulic systems. When selecting a hydraulic motor, the following factors should be considered: Since the displacement is inversely proportional to pressure at a constant load torque (i.e., higher pressure means smaller displacement and vice versa), displacement size is an important indicator of the motor’s working capability. The speed of the hydraulic motor should neither be too low nor too high. If the motor’s speed is too low, the instability caused by friction and leakage can result in crawling, which severely affects the smoothness of the working components. To expand the speed range, it is better to select a motor with a lower minimum speed.

Considerations for Selecting Hydraulic Control Valves: The rated pressure of a hydraulic valve should generally be close to its operating pressure. However, for systems with higher reliability requirements, the valve’s rated pressure should be significantly higher than its operating pressure.

Flow and Diameter Selection Considerations: Flow rate is mainly used to specify the size of medium- and low-pressure hydraulic valves. The rated flow of the valve should not differ greatly from its actual operating flow, as this would result in excessive volumetric loss. The nominal size of the inlet and outlet of the hydraulic valve is called the diameter, which is mainly used to specify the size of medium- and high-pressure hydraulic valves. However, hydraulic valves with the same diameter but different designs may have different rated flows under varying pressures. Designers should select the appropriate diameter based on operating pressure and flow rate, referring to the hydraulic valve characteristic curves provided by the hydraulic component manufacturers.